Sine-type pumps and sine-type motors (designed like pumps, but using a pressurized fluid to generate drive torque) are known in a variety of constructions.
U.S. Pat. No. 3,156,158 discloses a dental drilling apparatus comprising a sine-type motor. The housing of the motor has a hollow cylindrical configuration. A stator is disposed in the housing to be in contact with the outer circumferential surface of the web of the rotor for about 180°. The stator has a generally sleeve type configuration, but does not extend a full 360° circle and includes an axially extending, interrupting slot to retain the scraper by such slot. Sealing of the motor against leakage of the working fluid is effected by sealing rings placed near the axial end portions of the housing, relatively distant from the rotor web and the inlet and outlet ports.
The company MASO Process—Pumpen GmbH, 74358 Illsfeld, Germany, has produced and sold for a number of years a sine—pump having a stator extending somewhat more than 180° along the inner circumference of the housing. The portions of the housing, forming the inlet and outlet chambers, are not lined with the stator. The scraper is supported in the housing by means of a complicated support member. Seen in axial direction, the support member is inverted U-shaped and saddles the block-shaped scraper. The support member requires complicated machining.
It is an object of the invention to provide a sine-pump that allows relatively uncomplicated and inexpensive manufacture.